ioctl: Rearrange members in nvme_security_receive_args

Avoid any holes in the struct by rearranging the members. Also add the
attribute packed to struct definition to reduce ABI breakage.

struct nvme_security_receive_args {
        int                        args_size;            /*     0     4 */
        int                        fd;                   /*     4     4 */
        __u32 *                    result;               /*     8     8 */
        __u32                      timeout;              /*    16     4 */
        __u32                      nsid;                 /*    20     4 */
        __u8                       nssf;                 /*    24     1 */
        __u8                       spsp0;                /*    25     1 */
        __u8                       spsp1;                /*    26     1 */
        __u8                       secp;                 /*    27     1 */
        __u32                      al;                   /*    28     4 */
        void *                     data;                 /*    32     8 */
        __u32                      data_len;             /*    40     4 */

        /* size: 48, cachelines: 1, members: 12 */
        /* padding: 4 */
        /* last cacheline: 48 bytes */
} __attribute__((__aligned__(8)));

Signed-off-by: Daniel Wagner <[email protected]>

Author: dwsuse

src/nvme/ioctl.h

@@ -2971,31 +2971,31 @@ int nvme_security_send(struct nvme_security_send_args *args);
 /**
  * nvme_security_receive_args - Arguments for the NVMe Security Receive command
  * @fd:		File descriptor of nvme device
+ * @result:	The command completion result from CQE dword0
+ * @timeout:	Timeout in ms
  * @nsid:	Namespace ID to issue security command on
  * @nssf:	NVMe Security Specific field
  * @spsp0:	Security Protocol Specific field
  * @spsp1:	Security Protocol Specific field
  * @secp:	Security Protocol
  * @al:		Protocol specific allocation length
- * @data_len:	Data length of the payload in bytes
  * @data:	Security data payload to send
- * @timeout:	Timeout in ms
- * @result:	The command completion result from CQE dword0
+ * @data_len:	Data length of the payload in bytes
  */
 struct nvme_security_receive_args {
 	int args_size;
 	int fd;
+	__u32 *result;
+	__u32 timeout;
 	__u32 nsid;
 	__u8 nssf;
 	__u8 spsp0;
 	__u8 spsp1;
 	__u8 secp;
 	__u32 al;
-	__u32 data_len;
 	void *data;
-	__u32 timeout;
-	__u32 *result;
-};
+	__u32 data_len;
+} __attribute__((packed, aligned(__alignof__(__u32*))));
 
 /**
  * nvme_security_receive() -